He joined the Royal Air Force in 1933, and trained at Cranwell. He served in Training Command, and as a flying instructor at RAF Montrose. He was stationed at RAF Tangmere in 1937 and was a member of No. 43 Squadron RAF. The first enemy aircraft to crash on English soil during World War II fell victim to fighters from Acklington on 3 February 1940 when three Hurricanes of ‘B’ flight, 43 Squadron, shot down a Heinkel 111 of 4./KG 26 near Whitby. The pilots were F/L Townsend, F/O ‘Tiger’ Folkes and Sgt. James Hallowes. He was awarded the DFC in April 1940. Two more He 111s were claimed by Townsend, on 22 February and 8 April, and a sixth share on 22 April. Enemy aircraft had been shot down in 1939 by the RAF from over Scotland's Scapa Flow shipyards during the Luftwaffe's first raid on Britain.[1]

By May 1940, Townsend was one of the most capable squadron leaders of the Battle of Britain, serving throughout the battle as CO of No. 85 Squadron RAF, flying Hawker Hurricanes. On 11 July 1940 Townsend, flying Hurricane VY-K (P2716) intercepted a Dornier Do 17 of KG 2 and severely damaged the bomber, forcing it to crash land at Arras. Return fire from the Dornier hit the Hurricane coolant system and Townsend was forced to ditch 20 miles from the English coast, being rescued by HM Trawler Cape Finisterre. On 31 August, during combat with Bf 110s over Tonbridge, Townsend was shot down and wounded in the left foot by a cannon shell which went through the glycol tank and exploded in the cockpit. He continued to lead the unit on the ground even after this wound resulted in his big toe being amputated, and he returned to operational flying on 21 September. A bar to his DFC was awarded in early September 1940.

On 17 July 1941 Peter Townsend married (Cecil) Rosemary Pawle (1921–2004) with whom he had two sons, Giles (b. 1942) and Hugo (b. 1945). They divorced in 1952 and Rosemary later married John de László (son of the painter Philip de László) and became the third wife of the 5th Marquess Camden in 1978.

Townsend later married a Belgian woman, Marie-Luce Jamagne, in 1959.[2] Their daughter, Isabelle Townsend, became a Ralph Lauren advertising model in the late 1980s and early 1990s. Isabelle and her family live in a house in France named "The Mill," where the Duke and Duchess of Windsor once resided.[3]

Group Captain Townsend is best known for his romance with Princess Margaret.[4] He had met the Princess in his role as an equerry to her father, King George VI. Despite his distinguished career, divorced people suffered severe disapproval in the social atmosphere of the time, and could not remarry in the Church of England. Thus Townsend had no chance of marriage with the princess unless she renounced her royal privileges. Their relationship caused enormous controversy after Margaret's sister acceded to the throne. The Princess eventually renounced Townsend, who was sent to take up a post at the British Embassy in Belgium.

Although Princess Margaret later married photographer Anthony Armstrong-Jones in 1960, she herself divorced in 1978.

Peter Townsend spent much of his later years writing non-fiction books. His books include Earth My Friend (about driving/boating around the world alone in the mid-1950s), Duel of Eagles (about the Battle of Britain), The Odds Against Us (also known as Duel in the Dark) (about fighting Luftwaffe night bombers in 1940-1941), The Last Emperor (a biography of King George VI), The Girl in the White Ship (about a young refugee from Vietnam in the late 1970s who was the sole survivor of her ship of refugees), The Postman of Nagasaki (about the atomic bombing of Nagasaki), and Time and Chance (an autobiography). He also wrote many short articles and contributed to other books.

Peter Townsend was one of several military advisors for the film Battle of Britain (1969), and he also appeared in the PBS video, The Windsors: A Royal Family (1994).

He was a CVO (1947), DSO (1941) and DFC (1940 and bar). Townsend died of stomach cancer in 1995, at the age of 80, in Rambouillet, France. A sculpture of Group Captain Townsend stands in Townsend Square, part of the Kings Hill development on the site formerly occupied by RAF West Malling.[5]